In short, Sencha Cmd is an executable that provides a series of further commands to assist with your Sencha application development. Under the hood, it comprises a number of third-party utilities and scripts that combine to provide this functionality. Here are a few of the things it bundles in its installation:

All of this is tied together with some custom glue from Sencha, supported by Apache Ant—a build tool commonly used in the Java world.

The result is a complex yet powerfully customizable tool. The use of Ant allows almost all of the features of Sencha Cmd to be tweaked and extended, while Sencha's additions provide a straightforward command-line interface to this power.

For the application...